Because the ignition process has a considerable effect on the efficiency of an internal combustion engine, and especially at a given engine output also largely determines the fuel consumption and pollutant emission, in the past extensive efforts have been made to optimize the ignition process. The currently most common ignition devices use spark plugs which ignite the fuel-air mixture. These spark plugs can have one or more electrodes. Each of these electrodes produces an ignition spark which ignites the fuel-air mixture in the immediate vicinity of the electrode. Combustion begins accordingly first in a very small starting volume around the electrodes of the spark plugs. Subsequently combustion propagates with an admittedly limited velocity.
DE 195 27 873 A1 and U.S. Pat. No. 5,136,944 describe a glow plug having a catalytic surface coating of the glow part for reducing the power consumption required for ignition. The disadvantages involve the production costs due to the required catalyst materials being increased, and the combustion process only insignificantly being optimized. U.S. Pat. No. 4,774,914 and U.S. Pat. No. 6,595,194 describe an ignition device which is designed to generate an especially large ignition spark.
U.S. Pat. No. 4,113,315 describes a two-chamber ignition process in which the fuel-air mixture is ignited by an ignition source in a first, small ignition space. Then, the fuel-air mixture is ignited by the flame propagation occurring in a larger second space, the actual cylinder. U.S. Pat. No. 4,499,872 shows a development of this two-chamber ignition process in which a mixture of ionized water and fuel is ignited using magnetic fields and ignition rods. It is common to the two-chamber ignition processes that they require high construction, and thus, production cost.
U.S. Pat. Nos. 5,673,554 and 5,689,949 disclose ignition processes in which microwave energy is used to produce in the combustion space a plasma which ignites the fuel-air mixture. The formation of the plasma is dependent largely on adherence to narrow boundary conditions with respect to formation of a resonant mode. This arrangement leads to considerable construction effort, especially with respect to the engine pistons which move up and down. Moreover, the microwave transmitter limits the path of piston motion in the engine. The corresponding features also apply to U.S. Pat. No. 5,845,480.
U.S. Pat. No. 5,983,871 describes a combination of injection of microwave and laser energy for producing the plasma. In this way, the complexity of the ignition device and of the ignition process as well as the pertinent engine is further increased. The corresponding also applies to U.S. Pat. No. 6,581,581 which describes a combination of ignition by microwave plasma and magnetic ionization of the atomized fuel-air mixture.
The known processes commonly require complex, and thus, expensive and high-maintenance structures. Moreover, they have only a limited service life. The efficiency of the combustion process, and therefore, of the engine driven by it are limited. In addition, the emission of pollutants is not adequately reduced. In particular, a lower combustion temperature is achieved by the leaning of the fuel-air mixture which has taken place for purposes of reduction of the fuel consumption. This leaning entails less power. The lower combustion temperature also leads to increased pollutant emission.